Perhaps 'rational' is too broad, as it seems the author means rationally probable, rather than rationally definite - we have "faith" in a large number of things that we don't actually see or know personally, but we have rational reason to believe or more likely to be true than not. If I rationally believe it is probable that a knife is holding will cut the bread I want to eat, this requires little faith because if it doesn't I can just grab another knife. When it comes to believing in something intangible like a religion, rational probability may take an individual to one level of certainty based on their experiences which deny or confirm the implications of that belief. However their faith to act further on those implications may be a matter of faith based on the potential risks. the author writes in the full paper:

A person might have faith in God when it comes to giving weekly donations to the poor but lack faith in God when it comes to allowing himself to be martyred.